Valve apparatus for an internal combustion engine

ABSTRACT

A method includes operating an internal combustion engine according to a four-stroke combustion cycle. The four-stroke combustion cycle includes a combustion stroke, an exhaust stroke, an intake stroke and a compression stroke. A valve associated with a cylinder of the internal combustion engine is opened at a first time during the four-stroke combustion cycle. The valve is closed at a second time during the four-stroke combustion cycle. The valve is opened at a third time during the four-stroke combustion cycle. The valve is closed at a fourth time during the four-stroke combustion cycle.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.11/534,519 entitled “Valve Apparatus for an Internal Combustion Engine,”and filed Sep. 22, 2006, which claims priority to U.S. ProvisionalApplication Ser. No. 60/719,506 entitled “Side Cam Open Port,” filedSep. 23, 2005 and U.S. Provisional Application Ser. No. 60/780,364entitled “Side Cam Open Port Engine with Improved Head Valve,” filedMar. 9, 2006; each of which is incorporated herein by reference in itsentirety.

This application is related to copending U.S. patent application Ser.No. 11/534,508 entitled “Valve Apparatus for an Internal CombustionEngine,” filed on Sep. 22, 2006, which is incorporated herein byreference in its entirety.

BACKGROUND

The invention relates generally to an apparatus for controlling gasexchange processes in a fluid processing machine, and more particularlyto a valve and cylinder head assembly for an internal combustion engine.

Many fluid processing machines, such as, for example, internalcombustion engines, compressors, and the like, require accurate andefficient gas exchange processes to ensure optimal performance. Forexample, during the intake stroke of an internal combustion engine, apredetermined amount of air and fuel must be supplied to the combustionchamber at a predetermined time in the operating cycle of the engine.The combustion chamber then must be sealed during the combustion eventto prevent inefficient operation and/or damage to various components inthe engine. During the exhaust stroke, the burned gases in thecombustion chamber must be efficiently evacuated from the combustionchamber.

Some known internal combustion engines use poppet valves to control theflow of gas into and out of the combustion chamber. Known poppet valvesare reciprocating valves that include an elongated stem and a broadenedsealing head. In use, known poppet valves open inwardly towards thecombustion chamber such that the sealing head is spaced apart from avalve seat, thereby creating a flow path into or out of the combustionchamber when the valve is in the opened position. The sealing head caninclude an angled surface configured to contact a corresponding surfaceon the valve seat when the valve is in the closed position toeffectively seal the combustion chamber.

The enlarged sealing head of known poppet valves, however, obstructs theflow path of the gas coming into or leaving the combustion cylinder,which can result in inefficiencies in the gas exchange process.Moreover, the enlarged sealing head can also produce vortices and otherundesirable turbulence within the incoming air, which can negativelyimpact the combustion event. To minimize such effects, some known poppetvalves are configured to travel a relatively large distance between theclosed position and the opened position. Increasing the valve lift,however, results in higher parasitic losses, greater wear on the valvetrain, greater chance of valve-to-piston contact during engineoperation, and the like.

Because the sealing head of known poppet valves extends into thecombustion chamber, they are exposed to the extreme pressures andtemperatures of engine combustion, which increases the likelihood thatthe valves will fail or leak. Exposure to combustion conditions cancause, for example, greater thermal expansion, detrimental carbondeposit build-up and the like. Moreover, such an arrangement is notconducive to servicing and/or replacing valves. In many instances, forexample, the cylinder head must be removed to service or replace thevalves.

Other known internal combustion engines use rotary valves to control theflow of gas into and out of the combustion chamber. Known rotary valvearrangements include a disc or cylinder having one or more openingsconfigured to align with corresponding ports in the cylinder head as thevalve continuously rotates, thereby creating a flow path into or out ofthe combustion chamber. Because such known rotary valves do not extendinto the combustion chamber, they address some of the disadvantages ofpoppet valves addressed above. Because of their continuous rotation,known rotary valves, however, are susceptible to valve leakage.Moreover, because of the continuous nature of operation, the timing ofthe valve events of known rotary valve engines is not easily varied.

Other known internal combustion engines use slide valves to control theflow of gas into and out of the combustion chamber. Known slide valvesare reciprocating valves that include an obstructing portion configuredto block the flow path into and/or out of the combustion chamber withoutany portion of the valve extending into the combustion chamber. Whileknown slide valve arrangements minimize some of the disadvantagesassociated with poppet valves, they are generally susceptible to valveleakage.

Other slide valves and rotary valves are known for use in fluid flowcontrol assemblies for low-pressure systems. Such assemblies, whilepotentially useful in controlling the flow of low-pressure liquids, areinadequate for use in high-pressure systems.

Thus, a need exists for an improved valve and cylinder head assembly foran internal combustion engine and like systems and devices.

SUMMARY

Gas exchange valves and methods are described herein. In one embodiment,a method includes operating a first cylinder defined by an internalcombustion engine in a combustion mode and operating selectively asecond cylinder defined by the internal combustion engine in one of acombustion mode or a pumping mode. When the first cylinder is operatingin the combustion mode, air is conveyed into the first cylinder from anintake manifold, the air is mixed with fuel and the mixture of the fueland the air is combusted within the first cylinder. When the secondcylinder is operating in the combustion mode, air is conveyed into thesecond cylinder from the intake manifold, the air is mixed with fuel andthe mixture of the fuel and the air is combusted within the secondcylinder. When the second cylinder is operating in the pumping mode, airis conveyed into the second cylinder from the intake manifold, the airis compressed without being mixed with fuel and without being combusted,and the compressed air is conveyed into the intake manifold from thesecond cylinder.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 and 2 are schematics illustrating a cylinder head assemblyaccording to an embodiment of the invention in a first configuration anda second configuration, respectively.

FIGS. 3 and 4 are schematics illustrating a cylinder head assemblyaccording to an embodiment of the invention in a first configuration anda second configuration, respectively.

FIG. 5 is a cross-sectional front view of a portion of an engineincluding a cylinder head assembly according to an embodiment of theinvention in a first configuration.

FIG. 6 is a cross-sectional front view of the cylinder head assemblyillustrated in FIG. 5 in a second configuration

FIG. 7 is a cross-sectional front view of the portion of the cylinderhead assembly labeled “7” in FIG. 5.

FIG. 8 is a cross-sectional front view of the portion of the cylinderhead assembly labeled “8” in FIG. 6.

FIG. 9 is a top view of a portion of cylinder head assembly according toan embodiment of the invention.

FIGS. 10 and 11 are top and front views, respectively, of the valvemember illustrated in FIG. 5.

FIG. 12 is a cross-sectional view of the valve member illustrated inFIG. 11 taken along line 12-12.

FIG. 13 is a perspective view of the valve member illustrated in FIGS.10-12.

FIG. 14 is a perspective view of a valve member according to anembodiment of the invention.

FIGS. 15 and 16 are top and front views, respectively, of a valve memberaccording to an embodiment of the invention.

FIG. 17 is a perspective view of a valve member according to anembodiment of the invention.

FIG. 18 is a perspective view of a valve member according to anembodiment of the invention.

FIG. 19 is a perspective view of a valve member according to anembodiment of the invention.

FIGS. 20 and 21 are front cross-sectional and side cross-sectionalviews, respectively, of a cylinder head assembly according to anembodiment of the invention.

FIG. 22 is a front cross-sectional view of a portion of a cylinder headassembly according to an embodiment of the invention.

FIG. 23 is a front cross-sectional view of a cylinder head assemblyaccording to an embodiment of the invention.

FIGS. 24 and 25 are front cross-sectional and side cross-sectionalviews, respectively, of a cylinder head assembly according to anembodiment of the invention.

FIG. 26 is a cross-sectional view of a valve member according to anembodiment of the invention.

FIG. 27 is a perspective view of a valve member according to anembodiment of the invention having a one-dimensional tapered portion.

FIG. 28 is a front view of a valve member according to an embodiment ofthe invention.

FIGS. 29 and 30 are front cross-sectional views of a portion of acylinder head assembly according to an embodiment of the invention in afirst configuration and a second configuration, respectively.

FIG. 31 is a top view of a portion of an engine according to anembodiment of the invention.

FIG. 32 is a schematic illustrating a portion of an engine according toan embodiment of the invention.

FIG. 33 is a schematic illustrating a portion of the engine shown inFIG. 32 operating in a pumping assist mode.

FIGS. 34-36 are graphical representations of the valve events of anengine according to an embodiment of the invention operating in a firstmode and second mode, respectively.

FIG. 37 is a perspective exploded view of the cylinder head assemblyshown in FIG. 5.

FIG. 38 is a flow chart illustrating a method of assembling an engineaccording to an embodiment of the invention.

FIG. 39 is a flow chart illustrating a method of repairing an engineaccording to an embodiment of the invention.

DETAILED DESCRIPTION

In some embodiments, a method includes operating a first cylinderdefined by an internal combustion engine in a combustion mode andoperating selectively a second cylinder defined by the internalcombustion engine in one of a combustion mode or a pumping mode. Whenthe first cylinder is operating in the combustion mode, air is conveyedinto the first cylinder from an intake manifold, the air is mixed withfuel and the mixture of the fuel and the air is combusted within thefirst cylinder. When the second cylinder is operating in the combustionmode, air is conveyed into the second cylinder from the intake manifold,the air is mixed with fuel and the mixture of the fuel and the air iscombusted within the second cylinder. When the second cylinder isoperating in the pumping mode, air is conveyed into the second cylinderfrom the intake manifold, the air is compressed without being mixed withfuel and without being combusted, and the compressed air is conveyedinto the intake manifold from the second cylinder.

In some embodiments, the operating selectively the second cylinder inthe pumping mode includes opening an intake valve associated with thesecond cylinder when the engine is in a first configuration to allow airto flow from the intake manifold into the second cylinder. The intakevalve is then closed when the internal combustion engine is in a secondconfiguration to fluidically isolate the second cylinder from the intakemanifold. The air contained within the second cylinder is thencompressed. The intake valve is then opened a second time when theengine is in a third configuration to allow the air contained with thesecond cylinder to flow from the second cylinder into the intakemanifold. The intake valve is then closed when the engine is in a fourthconfiguration to fluidically isolate the second cylinder from the intakemanifold.

In some embodiments, a processor-readable medium includes code to open avalve associated with a cylinder when an internal combustion engine isin a first configuration to allow a first gas to flow from a gasmanifold, such as an intake manifold and/or an exhaust manifold, intothe cylinder. The code is then configured to close the valve when theengine is in a second configuration to fluidically isolate the cylinderfrom the gas manifold. The code is configured to open the valve when theengine is in a third configuration to allow a second gas contained withthe cylinder to flow from the cylinder into the gas manifold. The codeis configured to close the valve when the engine is in a fourthconfiguration to fluidically isolate the cylinder from the gas manifold.

In some embodiments, an apparatus includes an engine block defining acylinder, a cylinder head and a controller. The cylinder head has anelectronically actuated valve member configured to control a flow of gasbetween the cylinder and a gas manifold. The controller is incommunication with the electronically actuated valve and is configuredto open the valve when the engine is in a first configuration to allow afirst gas to flow from the gas manifold into the cylinder, close thevalve when the internal combustion engine is in a second configurationto fluidically isolate the cylinder from the gas manifold open the valvewhen the engine is in a third configuration to allow a second gascontained with the cylinder to flow from the cylinder into the gasmanifold and close the valve when the engine is in a fourthconfiguration to fluidically isolate the cylinder from the gas manifold.

FIGS. 1 and 2 are schematic illustrations of a cylinder head assembly130 according to an embodiment of the invention in a first and secondconfiguration, respectively. The cylinder head assembly 130 includes acylinder head 132 and a valve member 160. The cylinder head 132 has aninterior surface 134 that defines a valve pocket 138 having alongitudinal axis Lp. The valve member 160 has tapered portion 162defining two flow passages 168 and having a longitudinal axis Lv. Thetapered portion 162 includes two sealing portions 172, each of which isdisposed adjacent one of the flow passages 168. The tapered portion 162includes a first side surface 164 and a second side surface 165. Thesecond side surface 165 of the tapered portion 162 is angularly offsetfrom the longitudinal axis Lv by a taper angle Θ, thereby producing thetaper of the tapered portion 162. Although the first side surface 164 isshown as being substantially parallel to the longitudinal axis Lv,thereby resulting in an asymmetrical tapered portion 162, in someembodiments, the first side surface 164 is angularly offset such thatthe tapered portion 162 is symmetrical about the longitudinal axis Lv.Although the tapered portion 162 is shown as including a linear taperdefining the taper angle Θ, in some embodiments the tapered portion 162can include a non-linear taper.

The valve member 160 is reciprocatably disposed within the valve pocket138 such that the tapered portion 162 of the valve member 160 can bemoved along the longitudinal axis Lv of the tapered portion 162 withinthe valve pocket 138. In use, the cylinder head assembly 130 can beplaced in a first configuration (FIG. 1) and a second configuration(FIG. 2). As illustrated in FIG. 1, when in the first configuration, thevalve member 160 is in a first position in which the sealing portions172 are disposed apart from the interior surface 134 of the cylinderhead 132 such that each flow passage 168 is in fluid communication withan area 137 outside of the cylinder head 132. As illustrated in FIG. 2,the cylinder head assembly 132 is placed into the second configurationby moving the valve member 160 inwardly along the longitudinal axis Lvin the direction indicated by the arrow labeled A. When in the secondconfiguration, the sealing portions 172 are in contact with a portion ofthe interior surface 134 of the cylinder head 132 such that each flowpassage 168 is fluidically isolated from the area 137 outside of thecylinder head 132.

Although the entire valve member 160 is shown as being tapered, in someembodiments, only a portion of the valve member is tapered. For example,as will be discussed herein, in some embodiments, a valve member caninclude one or more non-tapered portions. In other embodiments, a valvemember can include multiple tapered portions.

Although the flow passages 168 are shown as being substantially normalto the longitudinal axis Lv of the valve member 160, in someembodiments, the flow passages 168 can be angularly offset from thelongitudinal axis Lv. Moreover, in some embodiments, the longitudinalaxis Lv of the valve member 160 need not be coincident with thelongitudinal axis Lp of the valve pocket 138. For example, in someembodiments, the longitudinal axis of the valve member can be offsetfrom and parallel to the longitudinal axis of the valve pocket. In otherembodiments, the longitudinal axis of the valve can be disposed at anangle to the longitudinal axis of the valve pocket.

As illustrated, the longitudinal axis Lv of the tapered portion 162 iscoincident with the longitudinal axis of the valve member. Accordingly,throughout the specification, the longitudinal axis of the taperedportion may be referred to as the longitudinal axis of the valve memberand vice versa. In some embodiments, however, the longitudinal axis ofthe tapered portion can be offset from the longitudinal axis of thevalve member. For example, in some embodiments, the first stem portionand/or the second stem portion as described below can be angularlyoffset from the tapered portion such that the longitudinal axis of thevalve member is offset from the longitudinal axis of the taperedportion.

Although the cylinder head assembly 130 is illustrated as having a firstconfiguration (i.e., an opened configuration) in which the flow passages168 are in fluid communication with an area 137 outside of the cylinderhead 132 and second configuration (i.e., a closed configuration) inwhich the flow passages 168 are fluidically isolated from the area 137outside of the cylinder head 132, in some embodiments the firstconfiguration can be the closed configuration and the secondconfiguration can be the opened configuration. In other embodiments, thecylinder head assembly 130 can have more than two configurations. Forexample, in some embodiments, a cylinder head assembly can have multipleopen configurations, such as, for example, a partially openedconfiguration and a fully opened configuration.

FIGS. 3 and 4 are schematic illustrations of a portion of an engine 200according to an embodiment of the invention in a first and secondconfiguration, respectively. The engine 200 includes a cylinder headassembly 230, a cylinder 203 and a gas manifold 210. The cylinder 203 iscoupled to a first surface 235 of the cylinder head assembly 230 and canbe, for example, a combustion cylinder defined by an engine block (notshown). The gas manifold 210 is coupled to a second surface 236 of thecylinder head assembly 230 and can be, for example an intake manifold oran exhaust manifold. Although the first surface 235 and the secondsurface 236 are shown as being parallel to and disposed on oppositesides of the cylinder head 232 from each other, in other embodiments,the first surface and the second surface can be adjacent each other. Inyet other embodiments, the gas manifold and the cylinder can be coupledto the same surface of the cylinder head.

The cylinder head assembly 230 includes a cylinder head 232 and a valvemember 260. The cylinder head 232 has an interior surface 234 thatdefines a valve pocket 238 having a longitudinal axis Lp. The cylinderhead 232 also defines two cylinder flow passages 248 and two gasmanifold flow passages 244. Each of the cylinder flow passages 248 is influid communication with the cylinder 203 and the valve pocket 238.Similarly, each of the gas manifold flow passages 244 is in fluidcommunication with the gas manifold 210 and the valve pocket 238.Although each of the cylinder flow passages 248 is shown as beingfluidically isolated from the other cylinder flow passage 248, in otherembodiments, the cylinder flow passages 248 can be in fluidcommunication with each other. Similarly, although each of the gasmanifold flow passages 244 is shown as being fluidically isolated fromthe other gas manifold flow passage 244, in other embodiments, the gasmanifold flow passages 244 can be in fluid communication with eachother.

The valve member 260 has a tapered portion 262 having a longitudinalaxis Lv and a taper angle Θ with respect to the longitudinal axis Lv.The tapered portion 262 defines two flow passages 268 and includes twosealing portions 272, each of which is disposed adjacent one of the flowpassages 268. Although shown as being an asymmetrical taper in a singledimension, in some embodiments the tapered portion can be symmetricallytapered about the longitudinal axis Lv. In other embodiments, asdiscussed in more detail herein, the tapered portion can be tapered intwo dimensions about the longitudinal axis Lv.

The valve member 260 is disposed within the valve pocket 238 such thatthe tapered portion 262 of the valve member 260 can be moved along itslongitudinal axis Lv within the valve pocket 238. In use, the engine 200can be placed in a first configuration (FIG. 3) and a secondconfiguration (FIG. 4). As illustrated in FIG. 3, when in the firstconfiguration, the valve member 260 is in a first position in which eachflow passage 268 is in fluid communication with one of the cylinder flowpassages 248 and one of the gas manifold flow passages 244. In thismanner, the gas manifold 210 is in fluid communication with the cylinder203. Although the flow passages 268 are shown as being aligned with thecylinder flow passages 248 and the gas manifold flow passages 244 whenthe engine is in the first configuration, in other embodiments the flowpassages 268 need not be directly aligned. In other words, the flowpassages 268, 248, 24 may be offset when the engine 200 is in the firstconfiguration, but the gas manifold 210 is still in fluid communicationwith the cylinder 203.

As illustrated in FIG. 4, when the engine 200 is in the secondconfiguration, the valve member 260 is in a second position, axiallyoffset from the first position in the direction indicated by the arrowlabeled B. In the second configuration, the sealing portions 272 are incontact with a portion of the interior surface 234 of the cylinder head232 such that each flow passage 268 is fluidically isolated from thecylinder flow passages 248. In this manner, the cylinder 203 isfluidically isolated from the gas manifold 210.

FIG. 5 is a cross-sectional front view of a portion of an engine 300including a cylinder head assembly 330 in a first configurationaccording to an embodiment of the invention. FIG. 6 is a cross-sectionalfront view of the cylinder head assembly 330 in a second configuration.The engine 300 includes an engine block 302 and a cylinder head assembly330 coupled to the engine block 302. The engine block 302 defines acylinder 303 having a longitudinal axis Lc. A piston 304 is disposedwithin the cylinder 303 such that it can reciprocate along thelongitudinal axis Lc of the cylinder 303. The piston 304 is coupled by aconnecting rod 306 to a crankshaft 308 having an offset throw 307 suchthat as the piston reciprocates within the cylinder 303, the crankshaft308 is rotated about its longitudinal axis (not shown). In this manner,the reciprocating motion of the piston 304 can be converted into arotational motion.

A first surface 335 of the cylinder head assembly 330 is coupled to theengine block 302 such a portion of the first surface 335 covers theupper portion of the cylinder 303 thereby forming a combustion chamber309. Although the portion of the first surface 335 covering the cylinder303 is shown as being curved and angularly offset from the top surfaceof the piston, in some embodiments, because the cylinder head assembly330 does not include valves that protrude into the combustion chamber,the surface of the cylinder head assembly forming part of the combustionchamber can have any suitable geometric design. For example, in someembodiments, the surface of the cylinder head assembly forming part ofthe combustion chamber can be flat and parallel to the top surface ofthe piston. In other embodiments, the surface of the cylinder headassembly forming part of the combustion chamber can be curved to form ahemispherical combustion chamber, a pent-roof combustion chamber or thelike.

A gas manifold 310 defining an interior area 312 is coupled to a secondsurface 336 of the cylinder head assembly 330 such that the interiorarea 312 of the gas manifold 310 is in fluid communication with aportion of the second surface 336. As described in detail herein, thisarrangement allows a gas, such as, for example air or combustionby-products, to be transported into or out of the cylinder 303 via thecylinder head assembly 330 and the gas manifold 310. Although shown asincluding a single gas manifold 310, in some embodiments, an engine caninclude two or more gas manifolds. For example, in some embodiments anengine can include an intake manifold configured to supply air and/or anair-fuel mixture to the cylinder head and an exhaust manifold configuredto transport exhaust gases away from the cylinder head.

Moreover, as shown, in some embodiments the first surface 335 can beopposite the second surface 336, such that the flow of gas into and/orout of the cylinder 303 can occur along a substantially straight line.In such an arrangement, a fuel injector (not shown) can be disposed inan intake manifold (not shown) directly above the cylinder flow passages348. In this manner, the injected fuel can be conveyed into the cylinder303 without being subjected to a series of bends. Eliminating bendsalong the fuel path can reduce fuel impingement and/or wall wetting,thereby leading to more efficient engine performance, such as, forexample, improved transient response.

The cylinder head assembly 330 includes a cylinder head 332 and a valvemember 360. The cylinder head 332 has an interior surface 334 thatdefines a valve pocket 338 having a longitudinal axis Lp. The cylinderhead 332 also defines four cylinder flow passages 348 and four gasmanifold flow passages 344. Each of the cylinder flow passages 348 isadjacent the first surface 335 of the cylinder head 332 and is in fluidcommunication with the cylinder 303 and the valve pocket 338. Similarly,each of the gas manifold flow passages 344 is adjacent the secondsurface 336 of the cylinder head 332 and is in fluid communication withthe gas manifold 310 and the valve pocket 338. Each of the cylinder flowpassages 348 is aligned with a corresponding gas manifold flow passage344. In this arrangement, when the cylinder head assembly 330 is in thefirst (or opened) configuration (see, e.g., FIGS. 5 and 7), the gasmanifold 310 is in fluid communication with the cylinder 303.Conversely, when the cylinder head assembly 330 is in a second (orclosed) configuration (see, e.g., FIGS. 6 and 8), the gas manifold 310is fluidically isolated from the cylinder 303.

The valve member 360 has tapered portion 362, a first stem portion 376and a second stem portion 377. The first stem portion 376 is coupled toan end of the tapered portion 362 of the valve member 360 and isconfigured to engage a valve lobe 315 of a camshaft 314. The second stemportion 377 is coupled to an end of the tapered portion 362 oppositefrom the first stem portion 376 and is configured to engage a spring318. A portion of the spring 318 is contained within an end plate 323,which is removably coupled to the cylinder head 332 such that itcompresses the spring 318 against the second stem portion 377 therebybiasing the valve member 360 in a direction indicated by the arrow D inFIG. 6.

The tapered portion 362 of the valve member 360 defines four flowpassages 368 therethrough. The tapered portion includes eight sealingportions 372 (see, e.g., FIGS. 10, 11 and 13), each of which is disposedadjacent one of the flow passages 368 and extends continuously aroundthe perimeter of an outer surface 363 of the tapered portion 362. Thevalve member 360 is disposed within the valve pocket 338 such that thetapered portion 362 of the valve member 360 can be moved along alongitudinal axis Lv of the valve member 360 within the valve pocket338. In some embodiments, the valve pocket 338 includes a surface 352configured to engage a corresponding surface 380 on the valve member 360to limit the range of motion of the valve member 360 within the valvepocket 338.

In use, when the camshaft 314 is rotated such that the eccentric portionof the valve lobe 315 is in contact with the first stem 376 of the valvemember 360, the force exerted by the valve lobe 315 on the valve member360 is sufficient to overcome the force exerted by the spring 318 on thevalve member 360. Accordingly, as shown in FIG. 5, the valve member 360is moved along its longitudinal axis Lv within the valve pocket 338 inthe direction of the arrow C, into a first position, thereby placing thecylinder head assembly 330 in the opened configuration. When in theopened configuration, the valve member 360 is positioned within thevalve pocket 338 such that each flow passage 368 is aligned with and influid communication with one of the cylinder flow passages 348 and oneof the gas manifold flow passages 344. In this manner, the gas manifold310 is in fluid communication with the cylinder 303, along the flow pathindicated by the arrow labeled E in FIG. 7.

When the camshaft 314 is rotated such that the eccentric portion of thecamshaft lobe 315 is not in contact with the first stem 376 of the valvemember 360, the force exerted by the spring 318 is sufficient to movethe valve member 360 in the direction of the arrow D, into a secondposition, axially offset from the first position, thereby placing thecylinder head assembly 330 in the closed configuration (see FIG. 6).When in the closed configuration, each flow passage 368 is offset fromthe corresponding cylinder flow passage 348 and gas manifold flowpassage 344. Moreover, as shown in FIG. 8, when in the closedconfiguration, each of the sealing portions 372 is in contact with aportion of the interior surface 334 of the cylinder head 332 such thateach flow passage 368 is fluidically isolated from the cylinder flowpassages 348. In this manner, the cylinder 303 is fluidically isolatedfrom the gas manifold 310.

Although the cylinder head assembly 330 is described as being configuredto fluidically isolate the flow passages 368 from the cylinder flowpassages 348 when in the closed configuration, in some embodiments, thesealing portions 372 can be configured to contact a portion of theinterior surface 334 of the cylinder head 332 such that each flowpassage 368 is fluidically isolated from the cylinder head flow passages348 and the gas manifold flow passages 344. In other embodiments, thesealing portions 372 can be configured to contact a portion of theinterior surface 334 of the cylinder head 332 such that each flowpassage 368 is fluidically isolated only from the gas manifold flowpassages 344.

Although each of the cylinder flow passages 348 is shown beingfluidically isolated from the other cylinder flow passage 348, in someembodiments, the cylinder flow passages 348 can be in fluidcommunication with each other. Similarly, although each of the gasmanifold flow passages 344 is shown being fluidically isolated from theother gas manifold flow passages 344, in other embodiments, the gasmanifold flow passages 344 can be in fluid communication with eachother.

Although the longitudinal axis Lc of the cylinder 303 is shown as beingsubstantially normal to the longitudinal axis Lp of the valve pocket 338and the longitudinal axis Lv of the valve 360, in some embodiments, thelongitudinal axis of the cylinder can be offset from the longitudinalaxis of the valve pocket and/or the longitudinal axis of the valvemember by an angle other than 90 degrees. In yet other embodiments, thelongitudinal axis of the cylinder can be substantially parallel to thelongitudinal axis of the valve pocket and/or the longitudinal axis ofthe valve member. Similarly, as described above, the longitudinal axisLv of the valve member 360 need not be coincident with or parallel tothe longitudinal axis Lp of the valve pocket 338.

In some embodiments, the camshaft 314 is disposed within a portion ofthe cylinder head 332. An end plate 322 is removably coupled to thecylinder head 332 to allow access to the camshaft 314 and the first stemportion 376 for assembly, repair and/or adjustment. In otherembodiments, the camshaft is disposed within a separate cam box (notshown) that is removably coupled to the cylinder head. Similarly, theend plate 323 is removably coupled to the cylinder head 332 to allowaccess to the spring 318 and/or the valve member 360 for assembly,repair, replacement and/or adjustment.

In some embodiments, the spring 318 is a coil spring configured to exerta force on the valve member 360 thereby ensuring that the sealingportions 372 remain in contact with the interior surface 334 when thecylinder head assembly 330 is in the closed configuration. The spring318 can be constructed from any suitable material, such as, for example,a stainless steel spring wire, and can be fabricated to produce asuitable biasing force. In some embodiments, however, a cylinder headassembly can include any suitable biasing member to ensure that that thesealing portions 372 remain in contact with the interior surface 334when the cylinder head assembly 330 is in the closed configuration. Forexample, in some embodiments, a cylinder head assembly can include acantilever spring, a Belleville spring, a leaf spring and the like. Inother embodiments, a cylinder head assembly can include an elasticmember configured to exert a biasing force on the valve member. In yetother embodiments, a cylinder head assembly can include an actuator,such as a pneumatic actuator, a hydraulic actuator, an electronicactuator and/or the like, configured to exert a biasing force on thevalve member.

Although the first stem portion 376 is shown and described as being indirect contact with the valve lobe 315 of the camshaft 314, in someembodiments, an engine and/or cylinder head assembly can include amember configured to maintain a predetermined valve lash setting, suchas for example, an adjustable tappet, disposed between the camshaft andthe first stem portion. In other embodiments, an engine and/or cylinderhead assembly can include a hydraulic lifter disposed between thecamshaft and the first stem portion to ensure that the valve member isin constant contact with the camshaft. In yet other embodiments, anengine and/or a cylinder head assembly can include a follower member,such as for example, a roller follower disposed between the first stemportion. Similarly, in some embodiments, an engine can include one ormore components disposed adjacent the spring. For example, in someembodiments, the second stem portion can include a spring retainer, suchas for example, a pocket, a clip, or the like. In other embodiments, avalve rotator can be disposed adjacent the spring.

Although the cylinder head 332 is shown and described as being aseparate component coupled to the engine block 302, in some embodiments,the cylinder head 332 and the engine block 302 can be monolithicallyfabricated, thereby eliminating the need for a cylinder head gasket andcylinder head mounting bolts. In some embodiments, for example, theengine block and the cylinder head can be cast using a single mold andsubsequently machined to include the cylinders, valve pockets and thelike. Moreover, as described above, the valve members can be installedand/or serviced by removing the end plate.

Although the engine 300 is shown and described as including a singlecylinder, in some embodiments, an engine can include any number ofcylinders in any arrangement. For example, in some embodiments, anengine can include any number of cylinders in an in-line arrangement. Inother embodiments, any number of cylinders can be arranged in a veeconfiguration, an opposed configuration or a radial configuration.

Similarly, the engine 300 can employ any suitable thermodynamic cycle.Such engine types can include, for example, Diesel engines, sparkignition engines, homogeneous charge compression ignition (HCCI)engines, two-stroke engines and/or four stroke engines. Moreover, theengine 300 can include any suitable type of fuel injection system, suchas, for example, multi-port fuel injection, direct injection into thecylinder, carburetion, and the like.

Although the cylinder head assembly 330 is shown and described above asbeing devoid of mounting holes, a spark plug, and the like, in someembodiments, a cylinder head assembly includes mounting holes, sparkplugs, cooling passages, oil drillings and the like.

Although the cylinder head assembly 330 is shown and described abovewith reference to a single valve 360 and a single gas manifold 310, insome embodiments, a cylinder head assembly includes multiple valves andgas manifolds. For example, FIG. 9 illustrates a top view of thecylinder head assembly 330 including an intake valve member 3601 and anexhaust valve member 360E. As illustrated, the cylinder head 332 definesan intake valve pocket 3381, within which the intake valve member 3601is disposed, and an exhaust valve pocket 338E, within which the exhaustvalve member 360E is disposed. Similar to the arrangement describedabove, the cylinder head 332 also defines four intake manifold flowpassages 3441, four exhaust manifold flow passages 344E and thecorresponding cylinder flow passages (not shown in FIG. 9). Each of theintake manifold flow passages 3441 is adjacent the second surface 336 ofthe cylinder head 332 and is in fluid communication with an intakemanifold (not shown) and the intake valve pocket 338I. Similarly, eachof the exhaust manifold flow passages 344E is adjacent the secondsurface 336 of the cylinder head 332 and is in fluid communication withan exhaust manifold (not shown) and the exhaust valve pocket 338E.

The operation of the intake valve member 3601 and the exhaust valvemember 360E is similar to that of the valve member 360 described abovein that each has a first (or opened) position and a second (or closed)position. In FIG. 9, the intake valve member 360I is shown in the openedposition, in which each flow passage 368I defined by the tapered portion362I of the intake valve member 360I is aligned with its correspondingintake manifold flow passage 344I and cylinder flow passage (not shown).In this manner, the intake manifold (not shown) is in fluidcommunication with the cylinder 303, thereby allowing a charge of air tobe conveyed from the intake manifold into the cylinder 303. Conversely,the exhaust valve member 360E is shown in the closed position in whicheach flow passage 368E defined by the tapered portion 362E of theexhaust valve member 360E is offset from its corresponding exhaustmanifold flow passage 344E and cylinder flow passage (not shown).Moreover, each sealing portion (not shown in FIG. 9) defined by theexhaust valve member 360E is in contact with a portion of the interiorsurface of the exhaust valve pocket 338E such that each flow passage368E is fluidically isolated from the cylinder flow passages (notshown). In this manner, the cylinder 303 is fluidically isolated fromthe exhaust manifold (not shown).

The cylinder head assembly 330 can have many different configurationscorresponding to the various combinations of the positions of the valvemembers 360I, 360E as they move between their respective first andsecond positions. One possible configuration includes an intakeconfiguration in which, as shown in FIG. 9, the intake valve member 360Iis in the opened position and the exhaust valve member 360E is in theclosed position. Another possible configuration includes a combustionconfiguration in which both valves are in their closed positions. Yetanother possible configuration includes an exhaust configuration inwhich the intake valve member 360I is in the closed position and theexhaust valve member 360E is in the opened position. Yet anotherpossible configuration is an overlap configuration in which both valvesare in their opened positions.

Similar to the operation described above, the intake valve member 360Iand the exhaust valve member 360E are moved by a camshaft 314 thatincludes an intake valve lobe 315I and an exhaust valve lobe 315E. Asshown, the intake valve member 360I and the exhaust valve member 360Eare each biased in the closed position by springs 318I, 318E,respectively. Although the intake valve lobe 315I and the exhaust valvelobe 315E are illustrated as being disposed on a single camshaft 314, insome embodiments, an engine can include separate camshafts to move theintake and exhaust valve members. In other embodiments, as discussedherein, the intake valve member 360I and/or the exhaust valve member360E can be moved by an suitable means, such as, for example, anelectronic solenoid, a stepper motor, a hydraulic actuator, a pneumaticactuator, a piezo-electric actuator or the like. In yet otherembodiments, the intake valve member 360I and/or the exhaust valvemember 360E are not maintained in the closed position by a spring, butrather include mechanisms similar to those described above for movingthe valve. For example, in some embodiments, a first stem of a valvemember can engage a camshaft valve lobe and the second stem of the valvemember can engage a solenoid configured to bias the valve member.

FIGS. 10-13 show a top view, a front view, a side cross-sectional viewand a perspective view of the valve member 360, respectively. Asdescribed above, the valve member has tapered portion 362, a first stemportion 376 and a second stem portion 377. The tapered portion 362 ofthe valve member 360 defines four flow passages 368. Each flow passage368 extends through the tapered portion 362 and includes a first opening369 and a second opening 370. In the illustrated embodiment, the flowpassages 368 are spaced apart by a distance S along the longitudinalaxis Lv of the tapered portion 362. The distance S corresponds to thedistance that the tapered portion 362 moves within the valve pocket 338when transitioning from the first (opened configuration) to the second(closed) configuration. Accordingly, the travel (or stroke) of the valvemember can be reduced by spacing the flow passages 368 closer together.In some embodiments, the distance S can be between 2.3 mm and 4.2 mm(0.090 in. and 0.166 in.). In other embodiments, the distance S can beless than 2.3 mm (0.090 in.) or greater than 4.2 mm (0.166 in.).Although illustrated as having a constant spacing S, in someembodiments, the flow passages are each separated by a differentdistance. As discussed in more detail herein, reducing the stroke of thevalve member can result in several improvements in engine performance,such as, for example, reduced parasitic losses, allowing the use ofweaker valve springs, and the like.

Although the tapered portion 362 is shown as defining four flow passageshaving a long, narrow shape, in some embodiments a valve member candefine any number of flow passages having any suitable shape and size.For example, in some embodiments, a valve member can include eight flowpassages configured to have approximately the same cumulative flow area(as taken along a plane normal to the longitudinal axis Lf of the flowpassages) as that of a valve member having four larger flow passages. Insuch an embodiment, the flow passages can be arranged such that thespacing between the flow passages of the “eight passage valve member” isapproximately half that of the of the spacing between the flow passagesof the “four passage valve member.” As such, the stroke of the “eightpassage valve member” is approximately half that of the “four passagevalve member,” thereby resulting in an arrangement that providessubstantially the same flow area while requiring the valve member tomove only approximately half the distance.

Each flow passage 368 need not have the same shape and/or size as theother flow passages 368. Rather, as shown, the size of the flow passagescan decrease with the taper of the tapered portion 362 of the valvemember 360. In this manner, the valve member 360 can be configured tomaximize the cumulative flow area, thereby resulting in more efficientengine operation. Moreover, in some embodiments, the shape and/or sizeof the flow passages 368 can vary along the longitudinal axis Lf. Forexample, in some embodiments, the flow passages can have a lead-inchamfer or taper along the longitudinal axis Lf.

Similarly, each of the manifold flow passages 344 and each of thecylinder flow passages 348 need not have the same shape and/or size asthe other manifold flow passages 344 and each of the cylinder flowpassages 348, respectively. Moreover, in some embodiments, the shapeand/or size of the manifold flow passages 344 and/or the cylinder flowpassages 348 can vary along their respective longitudinal axes. Forexample, in some embodiments, the manifold flow passages can have a leadin chamfer or taper along their longitudinal axes. In other embodiments,the cylinder flow passages can have a lead-in chamfer or taper alongtheir longitudinal axes.

Although the longitudinal axis Lf of the flow passages 368 is shown inFIG. 12 as being substantially normal to the longitudinal axis Lv of thevalve member 360, in some embodiments the longitudinal axis Lf of theflow passages 368 can be angularly offset from the longitudinal axis Lvof the valve member 360 by an angle other than 90 degrees. Moreover, asdiscussed in more detail herein, in some embodiments, the longitudinalaxis and/or the centerline of one flow passage need not be parallel tothe longitudinal axis of another flow passage.

As previously discussed with reference to FIG. 5, the valve member 360includes a surface 380 configured to engage a corresponding surface 352within the valve pocket 338 to limit the range of motion of the valvemember 360 within the valve pocket 338. Although the surface 380 isillustrated as being a shoulder-like surface disposed adjacent thesecond stem portion 377, in some embodiments, the surface 380 can haveany suitable geometry and can be disposed anywhere along the valvemember 360. For example, in some embodiments, a valve member can have asurface disposed on the first stem portion, the surface being configuredto limit the longitudinal motion of the valve member. In otherembodiments, a valve member can have a flattened surface disposed on oneof the stem portions, the flattened surface being configured to limitthe rotational motion of the valve member. In yet other embodiments, asillustrated in FIG. 37, the valve member 360 can be aligned using analignment key 398 configured to be disposed within a mating keyway 399.

As shown in FIG. 10, which illustrates a top view of the valve member360, the first opposing side surfaces 364 of the tapered portion 362 areangularly offset from each other by a first taper angle Θ. Similarly, asshown in FIG. 11, which presents a front view of the valve member 360,the second opposing side surfaces 365 of the tapered portion 362 areangularly offset from each other by an angle α. In this manner, thetapered portion 362 of the valve member 360 is tapered in twodimensions.

Said another way, the tapered portion 362 of the valve member 360 has awidth W measured along a first axis Y that is normal to the longitudinalaxis Lv. Similarly, the tapered portion 362 has a thickness T (not to beconfused with the wall thickness of any portion of the valve member)measured along a second axis Z that is normal to both the longitudinalaxis Lv and the first axis Y. The tapered portion 362 has atwo-dimensional taper characterized by a linear change in the width Wand a linear change in the thickness T. As shown in FIG. 10, the widthof the tapered portion 362 increases from a value of W1 at one end ofthe tapered portion 362 to a value of W2 at the opposite end of thetapered portion 362. The change in width along the longitudinal axis Lvdefines the first taper angle Θ. Similarly, as illustrated in FIG. 11,the thickness of the tapered portion 362 increases from a value of T1 atone end of the tapered portion 362 to a value of T2 at the opposite endof the tapered portion 362. The change in thickness along thelongitudinal axis Lv defines the second taper angle α.

In the illustrated embodiment, the first taper angle Θ and the secondtaper angle α are each between 2 and 10 degrees. In some embodiments,the first taper angle Θ is the same as the second taper angle α. Inother embodiments, the first taper angle Θ is different from the secondtaper angle α. Selection of the taper angles can affect the size of thevalve member and the nature of the seal formed by the sealing portions372 and the interior surface 334 of the cylinder head 332. In someembodiments, for example, the taper angles Θ, α can be as high as 90degrees. In other embodiments, the taper angles Θ, α can be as low as 1degree. In yet other embodiments, as discussed in more detail herein, avalve member can be devoid of a tapered portion (i.e., a taper angle ofzero degrees).

Although the tapered portion 362 is shown and described as having asingle, linear taper, in some embodiments a valve member can include atapered portion having a curved taper. In other embodiments, asdiscussed in more detail herein, a valve member can have a taperedportion having multiple tapers. Moreover, although the side surfaces164, 165 are shown as being angularly offset substantially symmetricalto the longitudinal axis Lv, in some embodiments, the side surfaces canbe angularly offset in an asymmetrical fashion.

As shown in FIGS. 10, 11 and 13, the tapered portion 362 includes eightsealing portions 372, each extending continuously around the perimeterof the outer surface 363 of the tapered portion 362. The sealingportions 372 are arranged such that two of the sealing portions 372 aredisposed adjacent each flow passage 368. In this manner, as shown inFIG. 8, when the cylinder head assembly 330 is in the closed positioneach of the sealing portions 372 is in contact with a portion of theinterior surface 334 of the cylinder head 332 such that each flowpassage 368 is fluidically isolated from the each cylinder flow passage348 and/or each gas manifold flow passage 344. Conversely, when thecylinder head assembly 330 is in the opened position each of the sealingportions 372 is disposed apart from the interior surface 334 of thecylinder head 332 such that each flow passage 368 is in fluidcommunication with the corresponding cylinder flow passages 348 and thecorresponding gas manifold flow passages 344.

Although the sealing portions 372 are shown and described as extendingaround the perimeter of the outer surface 363 substantially normal tothe longitudinal axis Lv of the valve member 360, in some embodiments,the sealing portions can be at any angular relation to the longitudinalaxis Lv. Moreover, in some embodiments, the sealing portions 372 can beangularly offset from each other.

Although the sealing portions 372 are shown and described as being alocus of points continuously extending around the perimeter of the outersurface 363 of the tapered portion 362 in a linear fashion when viewedin a plane parallel to the longitudinal axis Lv and the first axis Y(i.e., FIG. 10), in some embodiments, the sealing portions cancontinuously extend around the outer surface in a non-linear fashion.For example, in some embodiments, the sealing portions, when viewed in aplane parallel to the longitudinal axis Lv and the first axis Y, can becurved. In other embodiments, for example, as shown in FIG. 14, thesealing portions can be two-dimensional. FIG. 14 shows a valve member460 having a tapered portion 472, a first stem portion 476 and a secondstem portion 477. As described above, the tapered portion includes fourflow passages 468 therethrough. The tapered portion also includes twosealing portions 472 disposed about each flow passage 468 and extendingcontinuously around the perimeter of the outer surface 463 of thetapered portion 462 (for clarity, only two sealing portions 472 areshown). In contrast to the sealing portions 372 described above, thesealing portions 472 have a width X as measured along the longitudinalaxis Lv of the valve member 460.

As illustrated in FIG. 12, the tapered portion 362 has an ellipticalcross-section, which can allow for both a sufficient taper and flowpassages of sufficient size. In other embodiments, however, the taperedportion can have any suitable cross-sectional shape, such as, forexample, a circular cross-section, a rectangular cross-section and thelike.

As shown in FIGS. 10-13, the valve member 360 is monolithically formedto include the first stem portion 376, the second stem portion 377 andthe tapered portion 362. In other embodiments, however, the valve memberincludes separate components coupled together to form the first stemportion, the second stem portion and the tapered portion. In yet otherembodiments, the valve member does not include a first stem portionand/or a second stem portion. For example, in some embodiments, acylinder head assembly includes a separate component disposed within thevalve pocket and configured to engage a valve lobe of a camshaft and aportion of a valve member such that a force can be directly transmittedfrom the camshaft to the valve member. Similarly, in some embodiments, acylinder head assembly includes a separate component disposed within thevalve pocket and configured to engage a spring and a portion of a valvemember such that a force can be transmitted from the spring to the valvemember.

Although the sealing portions 372 and the outer surface 363 are shownand described as being monolithically constructed, in some embodiments,the sealing portions can be separate components coupled to the outersurface of the tapered portion. For example, in some embodiments, thesealing portions can be sealing rings that are held into mating grooveson the outer surface of the tapered portion by a friction fit. In otherembodiments, the sealing portions are separate components that arebonded to the outer surface of the tapered portion by any suitablemeans, such as, for example, chemical bonding, thermal bonding and thelike. In yet other embodiments, the sealing portions include a coatingapplied to the outer surface of the tapered portion by any suitablemanner, such as for example, electrostatic spray deposition, chemicalvapor deposition, physical vapor deposition, ionic exchange coating, andthe like.

The valve member 360 can be fabricated from any suitable material orcombination of materials. For example, in some embodiments, the taperedportion can be fabricated from a first material, the stem portions canbe fabricated from a second material different from the first materialand the sealing portions, to the extent that they are separately formed,can be fabricated from a third material different from the first twomaterials. In this manner, each portion of the valve member can beconstructed from a material that is best suited for its intendedfunction. For example, in some embodiments, the sealing portions can befabricated from a relatively soft stainless steel, such as for example,unhardened 430FR stainless steel, so that the sealing portions willreadily wear when contacting the interior surface of the cylinder head.In this manner, the valve member can be continuously lapped during use,thereby ensuring a fluid-tight seal. In some embodiments, for example,the tapered portion can be fabricated from a relatively hard materialhaving high strength, such as for example, hardened 440 stainless steel.Such a material can provide the necessary strength and/or hardness toresist failure that may result from repeated exposure to hightemperature exhaust gas. In some embodiments, for example, one or bothstem portions can be fabricated from a ceramic material configured tohave high compressive strength.

In some embodiments, the cylinder head 332, including the interiorsurface 334 that defines the valve pocket 338, is monolithicallyconstructed from a single material, such as, for example, cast iron. Insome monolithic embodiments, for example, the interior surface 334defining the valve pocket 338 can be machined to provide a suitablesurface for engaging the sealing portions 372 of the valve member 360such that a fluid-tight seal can be formed. In other embodiments,however, the cylinder head can be fabricated from any suitablecombination of materials. As discussed in more detail herein, in someembodiments, a cylinder head can include one or more valve insertsdisposed within the valve pocket. In this manner, the portion of theinterior surface configured to contact the sealing portions of the valvemember can be constructed from a material and/or in a manner conduciveto providing a fluid-tight seal.

Although the flow passages 368 are shown and described as extendingthrough the tapered portion 362 of the valve member 360 and having afirst opening 369 and a second opening 370, in other embodiments, theflow passages do not extend through the valve member. FIGS. 15 and 16show a top view and a front view, respectively, of a valve member 560according to an embodiment of the invention in which the flow passages568 extend around an outer surface 563 of the valve member 560. Similarto the valve member 360 described above, the valve member 560 includes afirst stem portion 576, a second stem portion 577 and a tapered portion562. The tapered portion 562 defines four flow passages 568 and eightsealing portions 572, each disposed adjacent to the edges of the flowpassages 568. Rather than extending through the tapered portion 562, theillustrated flow passages 568 are recesses in the outer surface 563 thatextend continuously around the outer surface 563 of the tapered portion562.

In other embodiments, the flow passages can be recesses that extend onlypartially around the outer surface of the tapered portion (see FIGS. 24and 25, discussed in more detail herein). In yet other embodiments, thetapered portion can include any suitable combination of flow passageconfigurations. For example, in some embodiments, some of the flowpassages can be configured to extend through the tapered portion whileother flow passages can be configured to extend around the outer surfaceof the tapered portion.

Although the valve members are shown and described above as includingmultiple sealing portions that extend around the perimeter of thetapered portion, in other embodiments, the sealing portion does notextend around the perimeter of the tapered portion. For example, FIG. 17shows a perspective view of a valve member 660 according to anembodiment of the invention in which the sealing portions 672 extendcontinuously around the openings 669 of the flow passages 668. Similarto the valve members described above, the valve member 660 includes afirst stem portion 676, a second stem portion 677 and a tapered portion662. The tapered portion 662 defines four flow passages 668 extendingtherethrough. Each flow passage 668 includes a first opening 669 and asecond opening (not shown) disposed opposite the first opening. Asdescribed above, the first opening and the second opening of each flowpassage 668 are configured to align with corresponding gas manifold flowpassages and cylinder flow passages, respectively, defined by thecylinder head (not shown).

The tapered portion 662 includes four sealing portions 672 disposed onthe outer surface 663 of the tapered portion 662. Each sealing portion672 includes a locus of points that extends continuously around a firstopening 669. In this arrangement, when the cylinder head assembly is inthe closed configuration, the sealing portion 672 contacts a portion ofthe interior surface (not shown) of the cylinder head (not shown) suchthat the first opening 669 is fluidically isolated from itscorresponding gas manifold flow passage (not shown). Although shown asincluding four sealing portions 672, each extending continuously arounda first opening 669, in some embodiments, the sealing portions canextend continuously around the second opening 670, thereby fluidicallyisolating the second opening from the corresponding cylinder flowpassage when the cylinder head assembly is in the closed configuration.In other embodiments, a valve member can include sealing portionsextending around both the first opening 669 and the second opening 670.

FIG. 18 shows a perspective view of a valve member 760 according to anembodiment of the invention in which the sealing portions 772 aretwo-dimensional. As illustrated, the valve member 760 includes a taperedportion 772, a first stem portion 776 and a second stem portion 777. Asdescribed above, the tapered portion includes four flow passages 768therethrough. The tapered portion also includes four sealing portions772 each disposed adjacent each flow passage 768 and extendingcontinuously around a first opening 769 of the flow passages 768. Thesealing portions 772 differ from the sealing portions 672 describedabove, in that the sealing portions 772 have a width X as measured alongthe longitudinal axis Lv of the valve member 760.

FIG. 19 shows a perspective view of a valve member 860 according to anembodiment of the invention in which the sealing portions 872 extendaround the perimeter of the tapered portion 862 and extend around thefirst openings 869. Similar to the valve members described above, thevalve member 860 includes a first stem portion 876, a second stemportion 877 and a tapered portion 862. The tapered portion 862 definesfour flow passages 868 extending therethrough. Each flow passage 868includes a first opening 869 and a second opening (not shown) disposedopposite the first opening. The tapered portion 862 includes sealingportions 872 disposed on the outer surface 863 of the tapered portion862. As shown, each sealing portion 872 extends around the perimeter ofthe tapered portion 862 and extends around the first openings 869. Insome embodiments, the sealing portions can comprise the entire spacebetween adjacent openings.

As discussed above, in some embodiments, a cylinder head can include oneor more valve inserts disposed within the valve pocket. For example,FIGS. 20 and 21 show a portion of a cylinder head assembly 930 having avalve insert 942 disposed within the valve pocket 938. The illustratedcylinder head assembly 930 includes a cylinder head 932 and a valvemember 960. The cylinder head 932 has a first exterior surface 935configured to be coupled to a cylinder (not shown) and a second exteriorsurface 936 configured to be coupled to a gas manifold (not shown). Thecylinder head 932 has an interior surface 934 that defines a valvepocket 938 having a longitudinal axis Lp. The cylinder head 932 alsodefines four cylinder flow passages 948 and four gas manifold flowpassages 944, configured in a manner similar to those described above.

The valve insert 942 includes a sealing portion 940 and defines fourinsert flow passages 945 that extend through the valve insert. The valveinsert 942 is disposed within the valve pocket 938 such that a firstportion of each insert flow passage 945 is aligned with one of the gasmanifold flow passages 944 and a second portion of each insert flowpassage 945 is aligned with one of the cylinder flow passages 948.

The valve member 960 has a tapered portion 962, a first stem portion 976and a second stem portion 977. The tapered portion 962 has an outersurface 963 and defines four flow passages 968 extending therethrough,as described above. The tapered portion 962 also includes multiplesealing portions (not shown) each of which is disposed adjacent one ofthe flow passages 968. The sealing portions can be of any type discussedabove. The valve member 960 is disposed within the valve pocket 938 suchthat the tapered portion 962 of the valve member 960 can be moved alonga longitudinal axis Lv of the valve member 960 within the valve pocket938 between an opened position (FIGS. 20 and 21) and a closed position(not shown). When in the opened position, the valve member 960 ispositioned within the valve pocket 938 such that each flow passage 968is aligned with and in fluid communication with one of the insert flowpassages 945, one of the cylinder flow passages 948 and one of the gasmanifold flow passages 944. Conversely, when in the closed position, thevalve member 960 is positioned within the valve pocket 938 such that thesealing portions are in contact with the sealing portion 940 of thevalve insert 942. In this manner, the flow passages 968 are fluidicallyisolated from the cylinder flow passages 948 and/or the gas manifoldflow passages 944.

As shown in FIG. 21, the valve pocket 938, the valve insert 942 and thevalve member 960 all have a circular cross-sectional shape. In otherembodiments, the valve pocket can have a non-circular cross-sectionalshape. For example, in some embodiments, the valve pocket can include analignment surface configured to mate with a corresponding alignmentsurface on the valve insert. Such an arrangement may be used, forexample, to ensure that the valve insert is properly aligned (i.e., thatthe insert flow passages 945 are rotationally aligned to be in fluidcommunication with the gas manifold flow passages 944 and the cylinderflow passages 948) when the valve insert 942 is installed into the valvepocket 938. In other embodiments, the valve pocket, the valve insertand/or the valve member can have any suitable cross-sectional shape.

The valve insert 942 can be coupled within the valve pocket 938 usingany suitable method. For example, in some embodiments, the valve insertcan have an interference fit with the valve pocket. In otherembodiments, the valve insert can be secured within the valve pocket bya weld, by a threaded coupling arrangement, by peening a surface of thevalve pocket to secure the valve insert, or the like.

FIG. 22 shows a cross-sectional view of a portion of a cylinder headassembly 1030 according to an embodiment of the invention that includesmultiple valve inserts 1042. Although FIG. 22 only shows one half of thecylinder head assembly 1030, one skilled in the art should recognizethat the cylinder head assembly is generally symmetrical about thelongitudinal axis Lp of the valve pocket, and is similar to the cylinderhead assemblies shown and described above. The illustrated cylinder headassembly 1030 includes a cylinder head 1032 and a valve member 1060. Asdescribed above, the cylinder head 1032 can be coupled to at least onecylinder and at least one gas manifold. The cylinder head 1032 has aninterior surface 1034 that defines a valve pocket 1038 having alongitudinal axis Lp. The cylinder head 1032 also defines three cylinderflow passages (not shown) and three gas manifold flow passages 1044.

As shown, the valve pocket 1038 includes several discontinuous, steppedportions. Each stepped portion includes a surface substantially parallelto the longitudinal axis Lp, through which one of the gas manifoldpassages 1044 extends. A valve insert 1042 is disposed within eachdiscontinuous, stepped portion of the valve pocket 1038 such that asealing portion 1040 of the valve insert 1042 is adjacent the taperedportions 1061 of the valve member 1060. In this arrangement, the valveinserts 1042 are not disposed about the gas manifold flow passages 1044and therefore do not have an insert flow passage of the type describedabove.

The valve member 1060 has a central portion 1062, a first stem portion1076 and a second stem portion 1077. The central portion 1062 includesthree tapered portions 1061, each disposed adjacent a surface that issubstantially parallel to the longitudinal axis of the valve member Lv.The central portion 1062 defines three flow passages 1068 extendingtherethrough and having an opening disposed on one of the taperedportions 1061. Each tapered portion 1061 includes one or more sealingportions of any type discussed above. The valve member 1060 is disposedwithin the valve pocket 1038 such that the central portion 1062 of thevalve member 1060 can be moved along a longitudinal axis Lv of the valvemember 1060 within the valve pocket 1038 between an opened position(shown in FIG. 22) and a closed position (not shown). When in the openedposition, the valve member 1060 is positioned within the valve pocket1038 such that each flow passage 1068 is aligned with and in fluidcommunication with one of the cylinder flow passages (not shown) and oneof the gas manifold flow passages 1044. Conversely, when in the closedposition, the valve member 1060 is positioned within the valve pocket1038 such that the sealing portions on the tapered portions 1061 are incontact with the sealing portion 1040 of the corresponding valve insert1042. In this manner, the flow passages 1068 are fluidically isolatedfrom the gas manifold flow passages 1044 and/or the cylinder flowpassages (not shown).

Although the cylinder heads are shown and described above as having thesame number of gas manifold flow passages and cylinder flow passages, insome embodiments, a cylinder head can have fewer gas manifold flowpassages than cylinder flow passages or vice versa. For example, FIG. 23shows a cylinder head assembly 1160 according to an embodiment of theinvention that includes a four cylinder flow passages 1148 by only onegas manifold flow passage 1144. The illustrated cylinder head assembly1130 includes a cylinder head 1132 and a valve member 1160. The cylinderhead 1132 has a first exterior surface 1135 configured to be coupled toa cylinder (not shown) and a second exterior surface 1136 configured tobe coupled to a gas manifold (not shown). The cylinder head 1132 has aninterior surface 1134 that defines a valve pocket 1138 within which thevalve member 1160 is disposed. As shown, the cylinder head 1132 definesfour cylinder flow passages 1148 and one gas manifold flow passage 1144,configured similar to those described above.

The valve member 1160 has a tapered portion 1162, a first stem portion1176 and a second stem portion 1177. The tapered portion 1162 definesfour flow passages 1168 extending therethrough, as described above. Thetapered portion 1162 also includes multiple sealing portions each ofwhich is disposed adjacent one of the flow passages 1168. The sealingportions can be of any type discussed above.

The cylinder head assembly 1130 differs from those described above inthat when the cylinder head assembly 1130 is in the closed configuration(see FIG. 23), the flow passages 1168 are not fluidically isolated fromthe gas manifold flow passage 1144. Rather, the flow passages 1168 areonly isolated from the cylinder flow passages 1148, in a mannerdescribed above.

Although the engines are shown and described as having a cylindercoupled to a first surface of a cylinder head and a gas manifold coupledto a second surface of a cylinder head, wherein the second surface isopposite the first surface thereby producing a “straight flow”configuration, the cylinder and the gas manifold can be arranged in anysuitable configuration. For example, in some instances, it may bedesirable for the gas manifold to be coupled to a side surface 1236 of athe cylinder head. FIGS. 24 and 25 show a cylinder head assembly 1230according to an embodiment of the invention in which the cylinder flowpassages 1248 are substantially normal to the gas manifold flow passages1244. In this manner, a gas manifold (not shown) can be mounted on aside surface 1236 of the cylinder head 1232.

The illustrated cylinder head assembly 1230 includes a cylinder head1232 and a valve member 1260. The cylinder head 1232 has a bottomsurface 1235 configured to be coupled to a cylinder (not shown) and aside surface 1236 configured to be coupled to a gas manifold (notshown). The side surface 1236 is disposed adjacent to and substantiallynormal to the bottom surface 1235. In other embodiments, the sidesurface can be angularly offset from the bottom surface by an angleother than 90 degrees. The cylinder head 1232 has an interior surface1234 that defines a valve pocket 1238 having a longitudinal axis Lp. Thecylinder head 1232 also defines four cylinder flow passages 1248 andfour gas manifold flow passages 1244. The cylinder flow passages 1248and the gas manifold flow passages 1244 differ from those previouslydiscussed in that the cylinder flow passages 1248 are substantiallynormal to the gas manifold flow passages 1244.

The valve member 1260 has a tapered portion 1262, a first stem portion1276 and a second stem portion 1277. The tapered portion 1262 includesan outer surface 1263 and defines four flow passages 1268. The flowpassages 1268 are not lumens that extend through the tapered portion1262, but rather are recesses in the tapered portion 1262 that extendpartially around the outer surface 1263 of the tapered portion 1262. Theflow passages 1268 include a curved surface 1271 to direct the flow ofgas through the valve member 1260 in a manner that minimizes the flowlosses. In some embodiments, a surface 1271 of the flow passages 1268can be configured to produce a desired flow characteristic, such as, forexample, a rotational flow pattern in the incoming and/or outgoing flow.

The tapered portion 1262 also includes multiple sealing portions (notshown) each of which is disposed adjacent one of the flow passages 1268.The sealing portions can be of any type discussed above. The valvemember 1260 is disposed within the valve pocket 1238 such that thetapered portion 1262 of the valve member 1260 can be moved along alongitudinal axis Lv of the valve member 1260 within the valve pocket1238 between an opened position (FIGS. 24 and 25) and a closed position(not shown), as described above.

Although the flow passages defined by the valve member have been shownand described as being substantially parallel to each other andsubstantially normal to the longitudinal axis of the valve member, insome embodiments the flow passages can be angularly offset from eachother and/or can be offset from the longitudinal axis of the valvemember by an angle other than 90 degrees. Such an offset may bedesirable, for example, to produce a desired flow characteristic, suchas, for example, swirl or tumble pattern in the incoming and/or outgoingflow. FIG. 26 shows a cross-sectional view of a valve member 1360according to an embodiment of the invention in which the flow passages1368 are angularly offset from each other and are not normal to thelongitudinal axis Lv. Similar to the valve members described above, thevalve member 1360 includes a tapered portion 1362 that defines four flowpassages 1368 extending therethrough. Each flow passage 1368 has alongitudinal axis Lf. As illustrated, the longitudinal axes Lf areangularly offset from each other. Moreover, the longitudinal axes Lf areoffset from the longitudinal axis of the valve member by an angle otherthan 90 degrees.

Although the flow passages 1368 are shown and described as having alinear shape and defining a longitudinal axis Lf, in other embodiments,the flow passages can have a curved shape characterized by a curvedcenterline. As described above, flow passages can be configured to havea curved shape to produce a desired flow characteristic in the gasentering and/or exiting the cylinder.

FIG. 27 is a perspective view of a valve member 1460 according to anembodiment of the invention that includes a one-dimensional taperedportion 1462. The illustrated valve member 1460 includes a taperedportion 1462 that defines three flow passages 1468 extendingtherethrough. The tapered portion includes three sealing portions 1472,each of which is disposed adjacent one of the flow passages 1468 andextends continuously around an opening of the flow passage 1468.

The tapered portion 1462 of the valve member 1460 has a width W measuredalong a first axis Y that is normal to a longitudinal axis Lv of thetapered portion 1462. Similarly, the tapered portion 1462 has athickness T measured along a second axis Z that is normal to both thelongitudinal axis Lv and the first axis Y. The tapered portion 1462 hasa one-dimensional taper characterized by a linear change in thethickness T. Conversely, the width W remains constant along thelongitudinal axis Lv. As shown, the thickness of the tapered portion1462 increases from a value of T1 at one end of the tapered portion 1462to a value of T2 at the opposite end of the tapered portion 1462. Thechange in thickness along the longitudinal axis Lv defines a taper angleα.

Although the valve members have been shown and described as including atleast one tapered portion that includes one or more sealing portions, insome embodiments, a valve member can include a sealing portion disposedon a non-tapered portion of the valve member. In other embodiments, avalve member can be devoid of a tapered portion. FIG. 28 is a front viewof a valve member 1560 that is devoid of a tapered portion. Theillustrated valve member 1560 has a central portion 1562, a first stemportion 1576 and a second stem portion 1577. The central portion 1562has an outer surface 1563 and defines three flow passages 1568 extendingcontinuously around the outer surface 1563 of the central portion 1562,as described above. The central portion 1562 also includes multiplesealing portions 1572 each of which is disposed adjacent one of the flowpassages 1568 and extends continuously around the perimeter of thecentral portion 1562.

In a similar manner as described above, the valve member 1560 isdisposed within a valve pocket (not shown) such that the central portion1562 of the valve member 1560 can be moved along a longitudinal axis Lvof the valve member 1560 within the valve pocket between an openedposition and a closed position. When in the opened position, the valvemember 1560 is positioned within the valve pocket such that each flowpassage 1568 is aligned with and in fluid communication with thecorresponding cylinder flow passages and gas manifold flow passages (notshown). Conversely, when in the closed position, the valve member 1560is positioned within the valve pocket such that the sealing portions1572 are in contact with a portion of the interior surface of thecylinder head, thereby are fluidically isolating the flow passages 1568.

As described above, the sealing portions 1572 can be, for example,sealing rings that are disposed within a groove defined by the outersurface of the valve member. Such sealing rings can be, for example,spring-loaded rings, which are configured to expand radially, therebyensuring contact with the interior surface of the cylinder head when thevalve member 1560 is in the closed position.

Conversely, FIGS. 29 and 30 show portion of a cylinder head assembly1630 that includes multiple 90 degree tapered portions 1631 in a firstand second configuration, respectively. Although FIGS. 29 and 30 onlyshow one half of the cylinder head assembly 1630, one skilled in the artshould recognize that the cylinder head assembly is generallysymmetrical about the longitudinal axis Lp of the valve pocket, and issimilar to the cylinder head assemblies shown and described above. Theillustrated cylinder head assembly 1630 includes a cylinder head 1632and a valve member 1660. The cylinder head 1632 has an interior surface1634 that defines a valve pocket 1638 having a longitudinal axis Lp andseveral discontinuous, stepped portions. The cylinder head 1632 alsodefines three cylinder flow passages (not shown) and three gas manifoldflow passages 1644.

The valve member 1660 has a central portion 1662, a first stem portion1676 and a second stem portion 1677. The central portion 1662 includesthree tapered portions 1661 and three non-tapered portions 1667. Thetapered portions 1661 each have a taper angle of 90 degrees (i.e.,substantially normal to the longitudinal axis Lv). Each tapered portion1661 is disposed adjacent one of the non-tapered portions 1667. Thecentral portion 1662 defines three flow passages 1668 extendingtherethrough and having an opening disposed on one of the non-taperedportions 1667. Each tapered portion 1661 includes a sealing portion thatextends around the perimeter of the outer surface of the valve member1660.

The valve member 1660 is disposed within the valve pocket 1638 such thatthe central portion 1662 of the valve member 1660 can be moved along alongitudinal axis Lv of the valve member 1660 within the valve pocket1638 between an opened position (shown in FIG. 29) and a closed position(shown in FIG. 30). When in the opened position, the valve member 1660is positioned within the valve pocket 1638 such that each flow passage1668 is aligned with and in fluid communication with one of the cylinderflow passages (not shown) and one of the gas manifold flow passages1644. Conversely, when in the closed position, the valve member 1660 ispositioned within the valve pocket 1638 such that the sealing portionson the tapered portions 1661 are in contact with a corresponding sealingportion 1640 defined by the valve pocket 1638. In this manner, the flowpassages 1668 are fluidically isolated from the gas manifold flowpassages 1644 and/or the cylinder flow passages (not shown).

Although some of the valve members are shown and described as includinga first stem portion configured to engage a camshaft and a second stemportion configured to engage a spring, in some embodiments, a valvemember can include a first stem portion configured to engage a biasingmember and a second stem portion configured to engage an actuator. Inother embodiments, an engine can include two camshafts, each configuredto engage one of the stem portions of the valve member. In this manner,the valve member can be biased in the closed position by a valve lobe onthe camshaft rather than a spring. In yet other embodiments, an enginecan include one camshaft and one actuator, such as, for example, apneumatic actuator, a hydraulic actuator, an electronic solenoidactuator or the like.

FIG. 31 is a top view of a portion of an engine 1700 according to anembodiment of the invention that includes both camshafts 1714 andsolenoid actuators 1716 configured to move the valve member 1760. Theengine 1700 includes a cylinder 1703, a cylinder head assembly 1730 anda gas manifold (not shown). The cylinder head assembly 1730 includes acylinder head 1732, an intake valve member 1760I and an exhaust valvemember 1760E. The cylinder head 1732 can include any combination of thefeatures discussed above, such as, for example, an intake valve pocket,an exhaust valve pocket, multiple cylinder flow passages, at least onemanifold flow passage and the like.

The intake valve member 1760I has tapered portion 1762I, a first stemportion 1776I and a second stem portion 1777I. The first stem portion1776I has a first end 1778I and a second end 1779I. Similarly, thesecond stem portion 1777I has a first end 1792I and a second end 1793I.The first end 1778I of the first stem portion 1776I is coupled to thetapered portion 1762I. The second end 1779I of the first stem portion1776I includes a roller-type follower 1790I configured to engage anintake valve lobe 1715I of an intake camshaft 1714I. The first end 1792Iof the second stem portion 1777I is coupled to the tapered portion1762I. The second end 1793I of the second stem portion 1777I is coupledto an actuator linkage 1796I, which is coupled a solenoid actuator1716I.

Similarly, the exhaust valve member 1760E has tapered portion 1762E, afirst stem portion 1776E and a second stem portion 1777E. A first end1778E of the first stem portion 1776E is coupled to the tapered portion1762E. A second end 1779E of the first stem portion 1776E includes aroller-type follower 1790E configured to engage an exhaust valve lobe1715E of an exhaust camshaft 1714E. A first end 1792E of the second stemportion 1777E is coupled to the tapered portion 1762E. A second end1793E of the second stem portion 1777E is coupled to an actuator linkage1796E, which is coupled a solenoid actuator 1716E.

In this arrangement, the valve members 1760I, 1760E can be moved by theintake valve lobe 1715I and the exhaust valve lobe 1715E, respectively,as described above. Additionally, the solenoid actuators 1716I, 1716Ecan supply a biasing force to bias the valve members 1760I, 1760E in theclosed position, as indicated by the arrows F (intake) and J (exhaust).Moreover, in some embodiments, the solenoid actuators 1716I, 1716E canbe used to override the standard valve timing as prescribed by the valvelobes 1715I, 1715E, thereby allowing the valves 1760I, 1760E to remainopen for a greater duration (as a function of crank angle and/or time).

Although the engine 1700 is shown and described as including a solenoidactuator 1716 and a camshaft 1714 for controlling the movement of thevalve members 1760, in other embodiments, an engine can include only asolenoid actuator for controlling the movement of each valve member. Insuch an arrangement, the absence of a camshaft allows the valve membersto be opened and/or closed in any number of ways to improve engineperformance. For example, as discussed in more detail herein, in someembodiments the intake and/or exhaust valve members can be cycled openedand closed multiple times during an engine cycle (i.e., 720 crankdegrees for a four stroke engine). In other embodiments, the intakeand/or exhaust valve members can be held in a closed position throughoutan entire engine cycle.

The cylinder head assemblies shown and described above are particularlywell suited for camless actuation and/or actuation at any point in theengine operating cycle. More specifically, as previously discussed,because the valve members shown and described above do not extend intothe combustion chamber when in their opened position, they will notcontact the piston at any time during engine operation. Accordingly, theintake and/or exhaust valve events (i.e., the point at which the valvesopen and/or close as a function of the angular position of thecrankshaft) can be configured independently from the position of thepiston (i.e., without considering valve-to-piston contact as a limitingfactor). For example, in some embodiments, the intake valve memberand/or the exhaust valve member can be fully opened when the piston isat top dead center (TDC).

Moreover, the valve members shown and described above can be actuatedwith relatively little power during engine operation, because theopening of the valve members is not opposed by cylinder pressure, thestroke of the valve members is relatively low and/or the valve springsopposing the opening of the valves can have relatively low biasingforce. For example, as discussed above, the stroke of the valve memberscan be reduced by including multiple flow passages therein and reducingthe spacing between the flow passages. In some embodiments, the strokeof a valve member can be 2.3 mm (0.090 in.).

In addition to directly reducing the power required to open the valvemember, reducing the stroke of the valve member can also indirectlyreduce the power requirements by allowing the use of valve springshaving a relatively low spring force. In some embodiments, the springforce can be selected to ensure that a portion of the valve memberremains in contact with the actuator during valve operation and/or toensure that the valve member does not repeatedly oscillate along itslongitudinal axis when opening and/or closing. Said another way, themagnitude of the spring force can be selected to prevent valve “bounce”during operation. In some embodiments, reducing the stroke of the valvemember can allow for the valve member to be opened and/or closed withreduced velocity, acceleration and jerk (i.e., the first derivative ofthe acceleration) profiles, thereby minimizing the impact forces and/orthe tendency for the valve member to bounce during operation. As aresult, some embodiments, the valve springs can be configured to have arelatively low spring force. For example, in some embodiments, a valvespring can be configured to exert a spring force of 110 N (50 lbf) whenthe valve member is both in the closed position and the opened position.

As a result of the reduced power required to actuate the valve members1760I, 1760E, in some embodiments, the solenoid actuators 1716I, 1716Ecan be 12 volt actuators requiring relatively low current. For example,in some embodiments, the solenoid actuators can operate on 12 volts witha current draw during valve opening of between 14 and 15 amperes ofcurrent. In other embodiments, the solenoid actuators can be 12 voltactuators configured to operate on a high voltage and/or current duringthe initial valve member opening event and a low voltage and/or currentwhen holding the valve member open. For example, in some embodiments,the solenoid actuators can operate on a “peak and hold” cycle thatprovides an initial voltage of between 70 and 90 volts during the first100 microseconds of the valve opening event.

In addition to reducing engine parasitic losses, the reduced powerrequirements and/or reduced valve member stroke also allow greaterflexibility in shaping the valve events. For example, in someembodiments the valve members can be configured to open and/or closesuch that the flow area through the valve member as a function of thecrankshaft position approximates a square wave.

As described above, in some embodiments, the intake valve member and/orthe exhaust valve member can be held open for longer durations, openedand closed multiple times during an engine cycle and the like. FIG. 32is a schematic of a portion of an engine 1800 according to an embodimentof the invention. The engine 1800 includes an engine block 1802 definingtwo cylinders 1803. The cylinders 1803 can be, for example, twocylinders of a four cylinder engine. A reciprocating piston 1804 isdisposed within each cylinder 1803, as described above. A cylinder head1830 is coupled to the engine block 1802. Similar to the cylinder headassemblies described above, the cylinder head 1830 includes twoelectronically actuated intake valves 1860I and two electronicallyactuated exhaust valves 1860E. The intake valves 1860I are configured tocontrol the flow of gas between an intake manifold 1810I and eachcylinder 1803. Similarly, the exhaust valves 1860E control the exchangeof gas between an exhaust manifold 1810E and each cylinder.

The engine 1800 includes an electronic control unit (ECU) 1896 incommunication with each of the intake valves 1860I and the exhaustvalves 1860E. The ECU is processor of the type known in the artconfigured to receive input from various sensors, determine the desiredengine operating conditions and convey signals to various actuators tocontrol the engine accordingly. In the illustrated embodiment, the ECU1896 is configured determine the appropriate valve events and provide anelectronic signal to each of the valves 1860I, 1860E so that the valvesopen and close as desired.

The ECU 1896 can be, for example, a commercially-available processingdevice configured to perform one or more specific tasks related tocontrolling the engine 1800. For example, the ECU 1896 can include amicroprocessor and a memory device. The microprocessor can be, forexample, an application-specific integrated circuit (ASIC) or acombination of ASICs, which are designed to perform one or more specificfunctions. In yet other embodiments, the microprocessor can be an analogor digital circuit, or a combination of multiple circuits. The memorydevice can include, for example, a read only memory (ROM) component, arandom access memory (RAM) component, electronically programmable readonly memory (EPROM), erasable electronically programmable read onlymemory (EEPROM), and/or flash memory.

Although the engine 1800 is illustrated and described as including anECU 1896, in some embodiments, an engine 1800 can include software inthe form of processor-readable code instructing a processor to performthe functions described herein. In other embodiments, an engine 1800 caninclude firmware that performs the functions described herein.

FIG. 33 is a schematic of a portion of the engine 1800 operating in a“cylinder deactivation” mode. Cylinder deactivation is a method ofimproving the overall efficiency of an engine by temporarilydeactivating the combustion event in one or more cylinders duringperiods in which the engine is operating at reduced loads (i.e. when theengine is producing a relatively low amount of torque and/or power),such as, for example, when a vehicle is operating at highway speeds.Operating at reduced loads is inherently inefficient due to, among otherthings, the high pumping losses associated with throttling the intakeair. In such instances, the overall engine efficiency can be improved bydeactivating the combustion event in one or more cylinders, whichrequires the remaining cylinders to operate at a higher load andtherefore with less throttling of the intake air, thereby reducing thepumping losses.

When the engine 1800 is operating in the cylinder deactivation mode,cylinder 1803A, which can be, for example cylinder #4 of a four cylinderengine, is the firing cylinder, operating on a standard four strokecombustion cycle. Conversely, cylinder 1803B, which can be, for example,cylinder #3 of a four cylinder engine, is the deactivated cylinder. Asshown in FIG. 33, the engine 1800 is configured such that the piston1804A within the firing cylinder 1803A is moving downwardly from topdead center (TDC) towards bottom dead center (BDC) on the intake stroke,as indicated by arrow AA. During the intake stroke, the intake valve1860IA is opened thereby allowing air or an air/fuel mixture to flowfrom the intake manifold 1810I into the cylinder 1803A, as indicated byarrow N. The exhaust valve 1860EA is closed, such that the cylinder1803A is fluidically isolated from the exhaust manifold 1810E.

Conversely, the piston 1804B within the deactivated cylinder 1803B ismoving upwardly from BDC towards TDC, as indicated by arrow BB. Asillustrated, the intake valve 1860IB is opened thereby allowing air toflow from the cylinder 1803B into the intake manifold 1810I, asindicated by arrow P. The exhaust valve 1860EB is closed such that thecylinder 1803B is fluidically isolated from the exhaust manifold 1810E.In this manner, the engine 1800 is configured so that cylinder 1803Boperates to pump air contained therein into the intake manifold 1810Iand/or cylinder 1803A. Said another way, cylinder 1803B is configured toact as a supercharger. In this manner, the engine 1800 can operate in a“standard” mode, in which cylinders 1803A and 1803B operate as naturallyaspirated cylinders to combust fuel and air, and a “pumping assist”mode, in which cylinder 1803B is deactivated and the cylinder 1803Aoperates as a boosted cylinder to combust fuel and air.

Although the engine 1800 is shown and described operating in a cylinderdeactivation mode in which one cylinder supplies air to anothercylinder, in some embodiments, an engine can operate in a cylinderdeactivation mode in which both the exhaust valve and the intake valveof the non-firing cylinder remain closed throughout the entire enginecycle. In other embodiments, an engine can operate in a cylinderdeactivation mode in which the intake valve and/or exhaust valve of thenon-firing cylinder is held open throughout the entire engine cycle,thereby eliminating the parasitic losses associated with pumping airthrough the non-firing cylinder. In yet other embodiments, an engine canoperate in a cylinder deactivation mode in which the non-firing cylinderis configured to absorb power from the vehicle, thereby acting as avehicle brake. In such embodiments, for example, the exhaust valve ofthe non-firing cylinder can be configured to open early so that thecompressed air contained therein is released without producing anyexpansion work.

FIGS. 34-36 are graphical representations of the valve events of acylinder of a multi-cylinder engine operating in a standard four strokecombustion mode, a first exhaust gas recirculation (EGR) mode and asecond EGR mode respectively. The longitudinal axes indicate theposition of the piston within the cylinder in terms of the rotationalposition of the crankshaft. For example, the position of 0 degreesoccurs when the piston is at top dead center on the firing stroke of theengine, the position of 180 degrees occurs when the piston is at bottomdead center after firing, the position of 360 degrees occurs when thepiston is at top dead center on the gas exchange stroke, and so on. Theregions bounded by dashed lines represent periods during which an intakevalve associated with the cylinder is opened. Similarly, the regionsbounded by solid lines represent the periods during which an exhaustvalve associated with the cylinder is opened.

As shown in FIG. 34, when the engine is operating in a four strokecombustion mode, the compression event 1910 occurs after the gaseousmixture is drawn into the cylinder. During the compression event 1910,both the intake and exhaust valves are closed as the piston movesupwardly towards TDC, thereby allowing the gaseous mixture contained inthe cylinder to be compressed by the motion of the piston. At a suitablepoint, such as, for example −10 degrees, the combustion event 1915begins. At a suitable point as the piston moves downwardly, such as, forexample, 120 degrees, the exhaust valve open event 1920 begins. In someembodiments, the exhaust valve open event 1920 continues until thepiston has reached TDC and has begun moving downwardly. Moreover, asshown in FIG. 34, the intake valve open event 1925 can begin before theexhaust valve open event 1920 ends. In some embodiments, for example,the intake valve open event 1925 can begin at 340 degrees and theexhaust valve open event 1920 can end at 390 degrees, thereby resultingin an overlap duration of 50 degrees. At a suitable point, such as, forexample, 600 degrees, the intake valve open event 1925 ends and a newcycle begins.

In some embodiments, a predetermined amount of exhaust gas is conveyedfrom the exhaust manifold to the intake manifold via an exhaust gasrecirculation (EGR) valve. In some embodiments, the EGR valve iscontrolled to ensure that precise amounts of exhaust gas are conveyed tothe intake manifold.

As shown in FIG. 35, when the engine is operating in the first EGR mode,the intake valve associated with the cylinder is configured to conveyexhaust gas from the cylinder directly into the intake manifold (notshown in FIG. 35), thereby eliminating the need for a separate EGRvalve. As shown, the compression event 1910′ occurs after the gaseousmixture is drawn into the cylinder. During the compression event 1910′,both the intake and exhaust valves are closed as the piston movesupwardly towards TDC, thereby allowing the gaseous mixture contained inthe cylinder to be compressed by the motion of the piston. As describedabove, at a suitable point, the combustion event 1915′ begins.Similarly, at a suitable point the exhaust valve open event 1920′begins. At a suitable point during the exhaust valve event 1920′, suchas, for example, at 190 degrees, the first intake valve open event 1950occurs. Because the first intake valve open event 1950 can be configuredto occur when the pressure of the exhaust gas within the cylinder isgreater than the pressure in the intake manifold, a portion of theexhaust gas will flow from the cylinder into the intake manifold. Inthis manner, exhaust gas can be conveyed directly into the intakemanifold via the intake valve. The amount of exhaust gas flow can becontrolled, for example, by varying the duration of the first intakevalve open event 1950, adjusting the point at which the first intakevalve open event 1950 occurs and/or varying the stroke of the intakevalve during the first intake valve open event 1950.

As shown in FIG. 35, the second intake valve open event 1925′ can beginbefore the exhaust valve open event 1920′ ends. As described above, atsuitable points, the first intake valve open event 1950 ends, the secondintake valve open event 1925′ ends and a new cycle begins.

As shown in FIG. 36, when the engine is operating in the second EGRmode, the exhaust valve associated with the cylinder is configured toconvey exhaust gas from the exhaust manifold (not shown) directly intothe cylinder (not shown in FIG. 35), thereby eliminating the need for aseparate EGR valve. As shown, the compression event 1910″ occurs afterthe gaseous mixture is drawn into the cylinder. During the compressionevent 1910″, both the intake and exhaust valves are closed as the pistonmoves upwardly towards TDC, thereby allowing the gaseous mixturecontained in the cylinder to be compressed by the motion of the piston.As described above, at a suitable point, the combustion event 1915″begins. Similarly, at a suitable point the first exhaust valve openevent 1920″ begins.

As described above, the intake valve open event 1925″ can begin beforethe first exhaust valve open event 1920″ ends. At a suitable pointduring the intake valve open event 1925″, such as, for example, at 500degrees, the second exhaust valve open event 1960 occurs. Because thesecond exhaust valve open event 1960 can be configured to occur when thepressure of the exhaust gas within the exhaust manifold is greater thanthe pressure in the cylinder, a portion of the exhaust gas will flowfrom the exhaust manifold into the cylinder. In this manner, exhaust gascan be conveyed directly into the cylinder via the exhaust valve. Theamount of exhaust gas flow into the cylinder can be controlled, forexample, by varying the duration of the second exhaust valve open event1960, adjusting the point at which the second exhaust valve open event1960 occurs and/or varying the stroke of the exhaust valve during thesecond exhaust valve open event 1960. As described above, at suitablepoints, the second exhaust valve open event 1970 ends, the intake valveopen event 1925″ ends and a new cycle begins.

Although the valve events are represented as square waves, in otherembodiments, the valve events can have any suitable shape. For example,in some embodiments the valve events can be configured to as sinusoidalwaves. In this manner, the acceleration of the valve member can becontrolled to minimize the likelihood of valve bounce during the openingand/or closing of the valve.

In addition to allowing improvements in engine performance, thearrangement of the valve members shown and described above also resultsin improvements in the assembly, repair, replacement and/or adjustmentof the valve members. For example, as previously discussed withreference to FIG. 5 and as shown in FIG. 37 the end plate 323 isremovably coupled to the cylinder head 332 via cap screws 317, therebyallowing access to the spring 318 and the valve member 360 for assembly,repair, replacement and/or adjustment. Because the valve member 360 doesnot extend below the first surface 335 of the cylinder head (i.e., thevalve member 360 does not protrude into the cylinder 303), the valvemember 360 can be installed and/or removed without removing the cylinderhead assembly 330 from the cylinder 303. Moreover, because the taperedportion 362 of the valve member 360 is disposed within the valve pocket338 such that the width and/or thickness of the valve member 360increases away from the camshaft 314 (e.g., in the direction indicatedby arrow C in FIG. 5), the valve member 360 can be removed withoutremoving the camshaft 314 and/or any of the linkages (i.e., tappets)that can be disposed between the camshaft 314 and the valve member 360.Additionally, the valve member 360 can be removed without removing thegas manifold 310. For example, in some embodiments, a user can removethe valve member 360 by moving the end plate 323 such that the valvepocket 338 is exposed, removing the spring 318, removing the alignmentkey 398 from the keyway 399 and sliding the valve member 360 out of thevalve pocket 338. Similar procedures can be followed to replace thespring 318, which may be desirable, for example, to adjust the biasingforce applied to the first stem portion 377 of the valve member 360.

Similarly, an end plate 322 (see FIG. 5) is removably coupled to thecylinder head 332 to allow access to the camshaft 314 and the first stemportion 376 for assembly, repair and/or adjustment. For example, asdiscussed in more detail herein, in some embodiments, a valve member caninclude an adjustable tappet (not shown) configured to provide apredetermined clearance between the valve lobe of the camshaft and thefirst stem portion when the cylinder head is in the closedconfiguration. In such arrangements, a user can remove the end plate 322to access the tappet for adjustment. In other embodiments, the camshaftis disposed within a separate cam box (not shown) that is removablycoupled to the cylinder head.

FIG. 38 is a flow chart illustrating a method 2000 for assembling anengine according to an embodiment of the invention. The illustratedmethod includes coupling a cylinder head to an engine block, 2002. Asdescribed above, in some embodiments, the cylinder head can be coupledto the engine block using cylinder head bolts. In other embodiments, thecylinder head and the engine block can be constructed monolithically. Insuch embodiments, the cylinder head is coupled to the engine blockduring the casting process. At 2004, a camshaft is then installed intothe engine.

The method then includes moving a valve member, of the type shown anddescribed above, into a valve pocket defined by the cylinder head, 2006.As previously discussed, in some embodiments, the valve member can beinstalled such that a first stem portion of the valve member is adjacentto and engages a valve lobe of the camshaft. Once the valve member isdisposed within the valve pocket, a biasing member is disposed adjacenta second stem portion of the valve member, 2008, and a first end plateis coupled to the cylinder head, such that a portion of the biasingmember engages the first end plate, 2010. In this manner, the biasingmember is retained in place in a partially compressed (i.e., preloaded)configuration. The amount of biasing member preload can be adjusted byadding and/or removing spacers between the first end plate and thebiasing member.

Because the biasing member can be configured to have a relatively lowpreload force, in some embodiments, the first end plate can be coupledto the cylinder head without using a spring compressor. In otherembodiments, the cap screws securing the first end plate to the cylinderhead can have a predetermined length such that the first end plate canbe coupled to the cylinder without using a spring compressor.

The illustrated method then includes adjusting a valve lash setting,2012. In some embodiments, the valve lash setting is adjusted byadjusting a tappet disposed between the first stem portion of the valvemember and the camshaft. In other embodiments, a method does not includeadjusting the valve lash setting. The method then includes coupling asecond end plate to the cylinder head, 2014, as described above.

FIG. 39 is a flow chart illustrating a method 2100 for replacing a valvemember in an engine without removing the cylinder head according to anembodiment of the invention. The illustrated method includes moving anend plate to expose a first opening of a valve pocket defined by acylinder head, 2102. In some embodiments, the end plate can be removedfrom the cylinder head. In other embodiments, the end plate can beloosened and pivoted such that the first opening is exposed. A biasingmember, which is disposed between a second end portion of the valvemember and the end plate, is removed, 2104. In this manner, the secondend portion of the valve member is exposed. The valve member is thenmoved from within the valve pocket through the first opening, 2106. Insome embodiments, the camshaft can be rotated to assist in moving thevalve member through the first opening. A replacement valve member isdisposed within the valve pocket, 2108. The biasing member is thenreplaced, 2110, and the end plate is coupled to the cylinder head 2112,as described above.

While various embodiments of the invention have been described above, itshould be understood that they have been presented by way of exampleonly, and not limitation. Where methods described above indicate certainevents occurring in certain order, the ordering of certain events may bemodified. Additionally, certain of the events may be performedconcurrently in a parallel process when possible, as well as performedsequentially as described above.

1. A method, comprising: operating an internal combustion engineaccording to a four-stroke combustion cycle, the four-stroke combustioncycle including a combustion stroke, an exhaust stroke, an intake strokeand a compression stroke; opening a valve associated with a cylinder ofthe internal combustion engine at a first time during the four-strokecombustion cycle; closing the valve at a second time during thefour-stroke combustion cycle; opening the valve at a third time duringthe four-stroke combustion cycle; and closing the valve at a fourth timeduring the four-stroke combustion cycle.
 2. The method of claim 1,wherein: a first gas flows from a manifold into the cylinder during atime period between the first time and the second time; and a second gasflows from the cylinder into the manifold during a time period betweenthe third time and the fourth time.
 3. The method of claim 1, wherein:the valve is an intake valve; the first time is during the exhauststroke of the four-stroke combustion cycle; and the intake stroke of thefour-stroke combustion cycle is defined by a time period between thethird time and the fourth time.
 4. The method of claim 1, wherein: thevalve is an intake valve; the first time is during the exhaust stroke ofthe four-stroke combustion cycle such that an exhaust gas flows from thecylinder into an intake manifold during a time period between the firsttime and the second time; and an intake gas flows from the intakemanifold to the cylinder during a time period between the third time andthe fourth time.
 5. The method of claim 1, wherein: the valve is anexhaust valve; the third time is during the intake stroke of thefour-stroke combustion cycle; and the exhaust stroke of the four-strokecombustion cycle is defined by a time period between the first time andthe second time.
 6. The method of claim 1, wherein: the valve is anexhaust valve; a first exhaust gas flows from an exhaust manifold to thecylinder during a time period between the first time and the secondtime; and the third time is during the intake stroke of the four-strokecombustion cycle such that a second exhaust gas flows from the cylinderinto the exhaust manifold during a time period between the third timeand the fourth time.
 7. A method, comprising: opening an intake valveassociated with a cylinder of an internal combustion engine at a firsttime when an exhaust valve associated with the cylinder of the internalcombustion engine is opened, the first time is during a combustioncycle; and closing the intake valve at a second time when the exhaustvalve is opened, the second time is during the combustion cycle afterthe first time.
 8. The method of claim 7, wherein: the first timecorresponds to a first rotational position of a crankshaft of theinternal combustion engine; and the second time corresponds to a secondrotational position of the crankshaft, the second rotational positionbeing less than approximately forty five degrees after the firstrotational position.
 9. The method of claim 7, further comprising:adjusting at least one of the first time or the second time such that aflow of an exhaust gas from the cylinder to an intake manifold via theintake valve is within a predetermined range.
 10. The method of claim 7,wherein: the opening includes opening the intake valve such that a firstportion of an exhaust gas flows from the cylinder into an intakemanifold through the intake valve after the opening; and a secondportion of the exhaust gas flows from the cylinder into an exhaustmanifold via the exhaust valve when the exhaust valve is opened.
 11. Themethod of claim 7, wherein the combustion cycle is a four-strokecombustion cycle.
 12. The method of claim 7, wherein the openingincludes opening the intake valve such that no portion of the intakevalve is within the cylinder.
 13. The method of claim 7, furthercomprising: opening the intake valve at a third time when the exhaustvalve is opened, the third time is during the combustion cycle after thesecond time.
 14. The method of claim 7, further comprising: opening theintake valve at a third time when the exhaust valve is opened, the thirdtime is during the combustion cycle after the second time; and closingthe exhaust valve at a fourth time, the fourth time is during thecombustion cycle after the third time.
 15. A method, comprising: openingan exhaust valve associated with a cylinder of an internal combustionengine at a first time when an intake valve associated with the cylinderof the internal combustion engine is opened, the first time is during acombustion cycle; and closing the exhaust valve at a second time whenthe intake valve is opened, the second time is during the combustioncycle after the first time.
 16. The method of claim 15, wherein: thefirst time corresponds to a first rotational position of a crankshaft ofthe internal combustion engine; and the second time corresponds to asecond rotational position of the crankshaft, the second rotationalposition being less than approximately forty five degrees after thefirst rotational position.
 17. The method of claim 15, furthercomprising: adjusting at least one of the first time or the second timesuch that a flow of a gas from an exhaust manifold to the cylinder viathe exhaust valve is within a predetermined range.
 18. The method ofclaim 15, wherein: the opening includes opening the exhaust valve suchthat an exhaust gas flows from an exhaust manifold into the cylinderthrough the exhaust valve after the opening; and an intake gas flowsfrom an intake manifold into the cylinder via the intake valve when theintake valve is opened.
 19. The method of claim 15, wherein the openingincludes opening the exhaust valve such that no portion of the exhaustvalve is within the cylinder.
 20. The method of claim 15, furthercomprising: opening the exhaust valve at a third time, the third time isduring the combustion cycle before the first time; and closing theexhaust valve at a fourth time, the fourth time is during the combustioncycle after the third time and before the first time.